<i>ortho</i>-Amidoalkylation of Phenols via Tandem One-Pot Approach Involving Oxazine Intermediate

A new and efficient method for <i>ortho</i>-amidoalkylation of phenols via Mannich-type condensation with formaldehyde and lactams using recyclable solid acid catalyst is described. This is the first report for <i>ortho</i>-amidoalkylation of phenols by lactams via Mannich-type condensation. LC-ESI-MS/MS based mechanistic study revealed that reaction proceeds through <i>o</i>-quinone methide (<i>o</i>-QM) and an oxazine intermediate via tandem Knoevenagel condensation, formal [4 + 2]-Diels–Alder cycloaddition and acid catalyzed oxazine ring-opening